1. Field of the Invention
The present invention relates to an image forming apparatus. More particularly, the present invention relates to an image forming apparatus suited for use as a copying machine, a printer (such as LED printer and laser beam printer), a facsimile machine, a word processor, and the like that are configured to form images on recording media by using an electrophotographic image forming process.
2. Description of the Related Art
Hitherto, in an image forming apparatus using an electrophotographic image forming process, there has been known an integrated cartridge system in which drums as photosensitive members (image bearing members) and developing units each housing a developing roller to act on the corresponding drum and each containing developer (toner) to be used for image formation are integrated with each other. Further, there have also been known a developing cartridge system in which the cartridge has only the developing units independently of the drums, and a drum cartridge system in which the cartridge has only the drums and process components to act on the corresponding drums. Those cartridge systems allow users themselves to perform maintenance of the apparatus without service engineers. Thus, those cartridge systems have been widely used in electrophotographic image forming apparatus.
Further, there has also been known a technology of arranging a support member to which integrated cartridges, developing cartridges, or drum cartridges are mounted, and pulling out the support member from an inside of a main body of the electrophotographic image forming apparatus to a predetermined position so that an operation of replacing various types of cartridges can be performed. The technology allows the users to easily replace the various types of cartridges.
As another example of the main body constructed as described above, there has been known a configuration in which shutter members are provided respectively on the cartridges, and the shutter members are moved to positions of protecting the corresponding drums (image bearing members) when the support member is pulled out, and to opening positions when the support member is located at a mounting position in the main body (Japanese Patent Application Laid-Open No. 2001-337580).
However, in such related art, the shutter members provided on the cartridges cause an increase in cost of the consumable cartridges, or an increase in size of the cartridges.